Prison structure



FIG. 1 is a front perspective view of a prison structure showing my newdesign;

FIG. 2 is a side elevational view the opposite side is a mirror imagethereof;

FIG. 3 is a front elevational view the rear is a mirror image thereof;and,

FIG. 4 is a top plan view thereof.

The ornamental design for a prison structure, as shown and described.